Thermo-mechanical challenges of advanced solar cell modules

This paper firstly summarizes the process flow developed at IMEC to integrate and interconnect thin back-contact solar cells into modules. Secondly, the process flow is simulated by Finite Element Modelling to determine critical process steps that may lead to early failures. A virtual Design of Experiment (DOE) is used to determine the best geometry and materials properties in order to minimise the induced stresses in the cells and the interconnections. The variables of this DOE are the silicon, the glue and the encapsulant thickness and the Elastic Modulus of the glue and encapsulant. The results of this DOE are presented in forms of Response Surface Models and it is observed that Young's Modulus of encapsulant and the thickness of the solar cells are the mayor contributors to the stresses in the silicon cells. Furthermore, an analysis of the changes in distance between adjacent cells at different temperatures indicates that the stiffness of the encapsulant material will play an important role on the mechanical behavior of the metallic solar cells interconnections.